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Filtering files by file extension

 

Applies to: Forefront Protection for Exchange

Topic Last Modified: 2010-05-11

You can filter e-mail attachments that have a certain file extension. To filter by file extension, create the filter list using the Filter files with specific name patterns option. In the file filter list, in the Filter criteria - by file name section, type an asterisk (*), add the extension on which you want to filter, and then add another * (this prevents files with extra characters appended after the file extension from bypassing the filter). Filter matching is not case-sensitive.

For example, to filter all files with an .exe extension, type the following file name: *.exe*.

noteNote:
It is recommended that you avoid using the * wildcard without specifying an extension and with all file types selected. This can result in every file being detected, regardless of the file name or extension.

When configuring filter lists in Forefront Protection 2010 for Exchange Server (FPE), we recommend that you create a file filter list for the transport scan that contains the file extensions of the file types that may potentially be infected by malware.

To create a file filter list containing potentially dangerous file extensions
  1. In the Forefront Protection 2010 for Exchange Server Administrator Console, click Policy Management, and then under the Filters section, click Configure.

  2. In the Filters – Filter Lists pane, click the Create button.

  3. In the Select Filter Type dialog box, select File and then click Next.

  4. In the Select Your Goal dialog box, select Filter files with specific name patterns and then click Next.

  5. In the Select File Names dialog box, specify the filter list name and filter details, and click Next when you are finished adding your criteria.

    1. In the Filter list name box, type a name for the new list.

    2. In the Filter criteria - by file name section, add the file extensions listed in the table at the end of this topic, and then click the Add button after each item. You can also add multiple file names on the same line, provided that they are separated by a comma. Or, you may want to add each item to a text file, placing each item on a separate line, and then import all the items by clicking the Import button. Each item should be added using the following format: *.extension*

  6. Click Next until you reach the Target dialog box. Review your settings (it is recommended that you keep the default values), and then click Create.

  7. Click Save.

The following table includes the file extensions that you should include as items in this file filter list. You should review this list periodically and update it as needed.

 

Extension

Type of file

*.ace*

Archive file

*.ade*

Microsoft Access project extension

*.adp*

Microsoft Access project

*.adt*

ACT! document template

*.app*

Executable application

*.asp*

Active Server Page files

*.arj*

Archive file

*.asd*

Word files that always have macros

*.bas*

Microsoft Visual Basic class module

*.bat*

Batch file

*.bin*

Binary file

*.btm*

Batch to memory batch file

*.cbt*

Computer based training

*.ceo*

Virus

*.chm*

Compiled HTML help file

*.cmd*

Microsoft Windows command script

*.cla*

Java class file

*.com*

Microsoft MS-DOS program

*.cpl*

Control Panel extension

*.crt*

Security certificate

*.csc*

Corel script file

*.css*

Cascading Style Sheet file

*.dll*

DLL files

*.drv*

Driver files

*.exe*

Program executable

*.email*

Outlook Express e-mail message

*.fon*

Font file

*.hlp*

Help file

*.hta*

HTML program

*.htm*

HTML files

*.inf*

Setup information

*.ins*

Internet naming service

*.isp*

Internet communication settings

*.je*

JScript file

*.js*

JScript file

*.jse*

JScript encoded script file

*.lib*

Program library common object file format

*.lnk*

Shortcut

*.mdb*

Access database file

*.mde*

MDE database file

*.mht*

Archived Web page

*.msc*

Microsoft common console document

*.msi*

Microsoft Windows installer package

*.mso*

Math script object file

*.msp*

Microsoft Windows installer patch

*.mst*

Microsoft Visual test source files

*.obj*

Relocatable object code

*.ocx*

Object Linking and Embedding control executable

*.ov*

OrgViewer file

*.pcd*

Photo CD image, Microsoft Visual compiled script

*.pgm*

CGI program

*.pif*

Shortcut to MS-DOS program

*.prc*

Palm Pilot resource file

*.rar*

Archive file

*.reg*

Registration entries

*.scr*

Screen saver

*.sct*

Windows script component

*.shb*

Shortcut into a document

*.shs*

Shell scrap object

*.smm*

AMI Pro macro

*.swf*

Macromedia files

*.sys*

System device driver

*.tar*

Archive file

*.url*

Internet shortcut

*.vb*

VBScript file

*.vxd*

Virtual device driver

*.wsc*

Windows script component

*.wsf*

Windows script file

*.wsh*

Windows script host settings file

*}*

CLSID filter

 
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